﻿/*
 * Copyright (c) 2015-2016 Constantijn Evenhuis (blueprints@const.nl)
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
using Blueprints.IO;
using Blueprints.Resolution;
using Blueprints.Validation;
using System;

namespace Blueprints.Defaults
{
    /// <summary>
    /// The default validation provider.
    /// </summary>
    public sealed class DefaultValidationProvider : IValidationProvider
    {
        private DefaultValidationContext currentContext;

        /// <summary>
        /// Creates a new DefaultValidationProvider.
        /// </summary>
        /// <param name="typeProvider">The type provider to use.</param>
        public DefaultValidationProvider(ITypeProvider typeProvider)
        {
            TypeProvider = typeProvider;
        }

        /// <summary>
        /// Gets the type provider to use.
        /// </summary>
        public ITypeProvider TypeProvider
        {
            get;
            private set;
        }

        /// <summary>
        /// Gets the current root serialization type.
        /// </summary>
        public string CurrentRootType
        {
            get;
            private set;
        }

        private DefaultValidationContext CurrentContext
        {
            get
            {
                return currentContext;
            }
            set
            {
                if (currentContext == value)
                {
                    return;
                }

                if (currentContext != null)
                {
                    currentContext.Dispose();
                }

                currentContext = value;
            }
        }

        /// <summary>
        /// Clears the cache, causing external documents to be inspected again.
        /// </summary>
        public void ClearCache()
        {
            DefaultValidationContext context = CurrentContext;
            if (context != null)
            {
                context.ClearResults();
            }
        }

        /// <summary>
        /// Validates a blueprint.
        /// </summary>
        /// <param name="reader">The reader to read the blueprint with.</param>
        /// <param name="rootType">The root serialization type.</param>
        /// <returns>The validated root node.</returns>
        public IValidatedNode Validate(IBlueprintReader reader, string rootType)
        {
            DefaultValidationContext context = GetContext(rootType);
            context.ClearResults(reader.DocumentUri);
            return context.Deserialize(reader);
        }

        void IDisposable.Dispose()
        {
            CurrentContext = null;
        }

        private DefaultValidationContext GetContext(string rootType)
        {
            if (string.Equals(rootType, CurrentRootType, StringComparison.Ordinal))
            {
                return CurrentContext;
            }

            CurrentRootType = rootType;
            Type type = Type.GetType(rootType) ?? typeof(object);
            CurrentContext = new DefaultValidationContext(TypeProvider, type);
            return CurrentContext;
        }
    }
}